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Hi, wondering if anyone has seen this before. At a job today and the supply to the 3 phase dust board is 2x16mm armours. One has three phases in it the other armour has the neutral and earth. Bit rough I think is there any regs on this ? Any help would be great.
 
I assume they pass through separate holes of a ferrous enclosure. See Reg 521.5.2
 
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They come through same holes to board separate glands obviously.
 
The glands are separate holes and assuming this is a ferrous enclosure then a slot should be cut between them.
 

Lucien Nunes

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Unbalanced currents in SWA conductors can cause circulating currents in the armour too. In some situations it is preferable for the armour to be connected at one end only to prevent this. In this case only the neutral current is unbalanced, consisting of up to one full line current and/or the zero sequence harmonics. In reality it's not likely to be a problem but it does have theoretical drawbacks.
 
The Regulations do not permit single core swa cables for ac circuits. You could argue the cable for the neutral and cpc breach this assuming it is referring to live conductors.
 

Lucien Nunes

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Large single-core cables are typically AWA rather than SWA, so there is no ferromagnetic component of the cable enclosing a longitudinal current. In any case on the supply side they aren't working to BS7671, which I had forgotten explicitly precluded 1c SWA for AC.
 

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